In order to maintain and improve the yields of products in the manufacturing line of semiconductor substrates, thin film substrates, or the like, defects on the surfaces of semiconductor substrates, thin film substrates, or the like are inspected. In the conventional techniques for inspecting defects, Japanese Patent Application Laid-Open Publication No. Hei-9-304289 (Patent Literature 1), Japanese Patent Application Laid-Open Publication No. 2006-201179 (Patent Literature 2), and US Patent Application Publication No. 2006/0256325(Patent Literature 3), and so on are known. These are techniques in order to detect defects in which luminous light is focused on a sample surface in a size of a few dozen μm, the light is applied to the sample surface, and the light scattered from defects is focused and detected for inspecting defects in a size of a few dozen nm or more and a few μm or more. A stage, on which a sample (an inspection object) is held, is rotated, moved, and translated, so that the light spot is helically scanned on the sample surface, and the entire surface of the sample is inspected.
Moreover, Patent Literature 1 and Patent Literature 2 describe techniques in which a component emitted at a high angle and a component emitted at a low angle in light scattered from a defect are detected, and defect types are sorted according to ratios between the components.
Furthermore, Patent Literature 2 describes a technique in which the size of a detected defect is calculated based on the intensity of the light scattered from the defect.
In addition, Patent Literature 3 describes that the power of luminous light, the scan speed of a light spot, or the size of a light spot is controlled in inspecting an inspection object surface in order to reduce thermal damage to a sample. More specifically, Patent Literature 3 describes that it is assumed that thermal damage to a sample is determined by the product of light power density and irradiation time and the power of luminous light, the scan speed of a light spot, or the size of a light spot is changed according to the radial position on the sample being scanned in such a way that the product does not exceed a certain value.
Moreover, U.S. Pat. No. 6,608,676 (Patent Literature 4) is known as a technique in which a sample is illuminated in a wide range with a Gaussian beam long in one direction and illuminated regions are collectively detected using a multi pixel detector such as a CCD for inspecting the entire surface of the sample for a short time.
Furthermore, Patent Literature 5 describes a method in which in short-wavelength laser illumination, there are many pulse beam emission lasers in high power lasers, and in order to reduce thermal damage to a sample due to a sudden temperature rise in the sample caused by instantaneous light emission, an optical path is divided and a pulse is divided using differences between the lengths of the optical paths for reducing damage to the sample.